It's no Magna Carta. Those of us who teach public law in British universities will certainly have to grapple with the Protection of Freedoms bill (pdf). But will it, like the that earlier constitutional text, echo through the centuries into the classrooms of 2311? I doubt it.

Although the bill's 107 sections will give Messrs Cameron and Clegg a long list of reforms to rattle off at party conferences, it does little to coherently explain the coalition's view of the appropriate relationship between the state and the citizen. The government does not know what freedom is, but it knows freedom isn't having your car immobilised without lawful authority (see section 54).

In many respects, the Protection of Freedoms bill seems to fit exactly with the coalition government's attitude towards 'freedom', 'liberty' or - perish the thought – 'human rights'. It is broadly libertarian but with no real coherent vision for fundamental rights. As a result, the Protection of Freedoms bill is a list of legislative pet hates, many introduced by New Labour, that the coalition wants to do away with.

The changes to counter-terrorism powers in part 4 may well indicate the character of the bill as a whole. Section 57 reduces the maximum period of pre-charge detention for terrorist offences from 28 days to 14. This is certainly a welcome move. The Terrorism Act 2000 originally provided for a 7 day detention period, which was increased to 14 days in 2003 and 28 days in 2006.

The act that provided for the latter increase, the Terrorism Act 2006, marked the high-point of the Blair government's counter-terrorism excesses. The 2005 bill had originally provided for an astounding 90 day period. So the reversion to 14 days is an improvement, but only against the backdrop of post-September 11 over-reaching. (And the government also announced, lest we forget, their backup plan).

Section 58 provides for the repeal of sections 44 to 47 of the Terrorism Act 2000. Good riddance. Section 44 was a wholly illiberal provision which allowed police officers to stop and search individuals in designated areas without having to show reasonable suspicion. The subsequent sections elaborated on that power. The government has been committed to repealing the section since last summer – but only after the European court of human rights held that it was a violation of the European Convention on Human Rights (ECHR).

Nonetheless, police powers abhor a vacuum, and as signalled in December, the section 44 power is replaced with new stop and search powers provided for by sections 59 to 62. The proposed new powers, at first glance, may be an improvement on section 44. But they have already been criticised and will require more considered scrutiny over the coming months – especially in light of possible amendments as the bill moves through Parliament.

Welcome though they may be, these changes do nothing to answer the more difficult questions about the appropriate role of state intervention in the face of violent politics. The vague offence of encouraging terrorism still blots the statute books while control orders continue in a new guise.

New Labour's flawed approach to the state-citizen relationship was to adopt the Human Rights Act at the start of their term and spend the remainder of it chipping away at the constitutional foundation provided by the Act. Today, there is, once more, a move on to end Britain's involvement in the ECHR once and for all. If the government jumps on that bandwagon, they will owe the constitution a replacement and this bill is certainly not it. It is piecemeal reform of selective aspects of several years worth of intrusive legislation. Progressive reform should always be welcomed but let's hold the fanfare. It's no Magna Carta.